There are many instances in industrial activity in which it is desirable to have a machine for comminuting odd-shaped pieces of rather tough material. An outstanding example of this need is in the plastic industry where a considerable amount of scrap is generated; this scrap exists in various forms and consists of somewhat resilient polymers. Such unruly scrap materials are difficult to cut into small pieces, because the shearing blades are subjected to extreme variations of stress due to the odd nature of the materials approaching the blades. The odd shapes are a contributing factor to clogging of the comminuting equipment not only in the feed hopper, but also in the area of the shearing knives. In the past, when it is necessary to unclog the hopper or the cutting blades, it was necessary to completely disassemble the comminuting machine. This meant that the machine was out of operation and presented problems so far as the flow of work through the plant was concerned. Another problem that has been experienced with the prior art comminuting machines is the matter of noise. The very fact that the cutting action is taking place within a hollow housing, means that the optimum conditions exist for the production of noise and no amount of resilient support is able to reduce this noise, as is possible in other types of machinery. Government agencies have insisted that sound levels be kept below a certain minimum and this is difficult to accomplish in a plant producing injection-molded plastics, for instance, where the only appreciable noise is in the comminuting machine. It would be possible, of course, to isolate the machine in its own separate room, but this presents other difficulties. First of all, because it is difficult to move materials in and out of such an isolation chamber and, secondly, it is desirable to be able to move the comminuting machine within the plant from one area of use to another. These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.
It is, therefore, an outstanding object of the invention to provide a granulator for effectively comminuting scraps consisting of odd-shaped pieces of a tough plastic.
Another object of this invention is the provision of a granulator having a rotary cutter whose bearings and cutting edges are capable of long life, despite use with tough, disorderly materials.
A further object of the present invention is the provision of a granulator having sound-absorbing means which does not interfere with repair of unclogging of the mechanism.
It is another object of the instant invention to provide a granulator which is mobile and yet does not require an isolating chamber to reduce its noise generation.
A still further object of the invention is the provision of a granulator in which noise generated is maintained at a minimum due to reduced thrust forces on the cutter spindle and readily removable sound-absorbing panels.
It is a further object of the invention to provide a granulator whose hood is readily removable from the comminuting area for access thereto without danger to the operator.
It is still further object of the present invention to provide a granulator whose cutting apparatus is efficient, so that relatively small amounts of horse power are required to drive it.
Another object of the invention is the provision of a granulator which is simple in construction, which is inexpensive to manufacture, and which is capable of a long life of useful service with a minimum of maintenance.
Another object of the invention is the provision of a granulator in which the cutting apparatus is arranged to distribute evenly the material to be comminuted throughout the chamber, so that uneven wear of the blade is prevented.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.